The overall goal of the proposed studies ion Project #1 is to improve our understanding of the mechanisms by which estrogen regulates ovarian follicular development. The four Specific Aims of this Project are designed to test the hypothesis that estradiol regulates follicular growth by: 1) controlling ovarian connective tissue remodeling via a family of proteolytic enzymes, the matrix metalloproteinases (MMPs; Aim #1, Dr. Curry), 2) regulating TGFbeta-activated intracellular signaling molecules known as SMADs (Aim #2, Dr. McGee), 3) modulating BRCA expression and oxidative DNA damage (Aim #3, Dr. Smith), and 4) regulating a family of nuclear receptors referred to as peroxisome proliferator-activated receptors (PPARs; Aim #4, Dr. Komar). It is hypothesized that there are dynamic, estradiol throughout the lifespan of the ovarian follicle. To test this hypothesis, changes in the localization and expression patterns of mRNA and protein for the MMPs, SMADs, BRCAs, and the PPARs will be determined during follicular development in: 1) prepubertal mice (increasing estradiol sensitivity), 2) adult mice (cyclic estradiol alter estradiol's action). Estradiol action will be evaluated in wild type mice versus mice lacking estrogen receptor alpha localization of the mRNA and protein for the endpoints associated with each Specific Aim (i.e. MMPs, SMADs, cellular localization patterns will be correlated with changes in the mRNA and protein expression pattern by RT-PCR, Northern analysis and Western blotting. The novelty of the experimental design in this Project is the shared use of the same tissues and techniques, thereby assuring that each Aim will be interactive with the others to develop an understanding of how estradiol regulates and coordinates these intra-ovarian factors during follicular growth and steroidogenesis. Therefore, a major strength of this proposal is our use of an integrated approach incorporating common model systems between all of the investigators to study the diverse actions of estrogen on folliculogenesis. The significance of the proposed studies is that they will provide a foundation to understand the physiological mechanisms of estrogen and SERM action on folliculogenesis thereby leading to future applications for promoting or inhibiting this crucial facet of ovarian biology.